Abstract:

This paper shows how soil micromorphology supports the study of archaeological earthen architecture. It allows us to infer (1) the provenience of raw materials according to the characteristic features of local soils; (2) the manufacturing process, indicating whether earth from several sources was mixed, whether mineral or vegetal tempers were added, and how much water was used; and (3) construction features and the degree of compaction using the shape and orientation of the components. This study is based on the microscopic analysis of thin sections of samples cut according to their position in the construction, allowing us to characterize mud bricks, renders ( from walls and floors), and cob. The research was carried out between 2019 and 2021 at the Universidad Nacional Autónoma de México (UNAM), within the framework of the CONACyT CB2015-254328 project, on almost one hundred samples of different types of walls, daub, plasters, and floors from fourteen Mesoamerican sites that date to the Preclassic and Classic periods, located in both semiarid and humid areas. To illustrate the procedure, we present examples of two mud bricks, two renders, and two experimental mud bricks from the archaeological site of La Joya, Veracruz, Mexico, and compare them to samples from the other sites. Our study shows that micromorphology is useful for correctly identifying construction techniques, basic information that is necessary for the adequate preservation of earthen heritage.